A Ukrainian drone struck an important arms depot inside Russia, the Ukraine military said Wednesday, three weeks after another drone blasted a major Russian armory and three days after a drone smashed into a key oil terminal in Russia-occupied Crimea.

The Tuesday night strike targeted an arsenal in Russia’s Bryansk border region where missiles and artillery munitions were stored, including some that had been delivered by North Korea, a Ukrainian General Staff statement said.

Hugely powerful glide bombs that have terrorized civilian areas of Ukraine and bludgeoned Ukrainian army defenses were also kept at the arsenal, located 115 kilometers (70 miles) from the Ukrainian border, and some of the ammunition was stored in the open, it said.

“Striking such arsenals creates serious logistical problems for the Russian army, thus significantly reducing (its) offensive capabilities,” the statement said.

Russia is expending enormous amounts of ammunition as it makes its advantage in artillery shells felt on the battlefield in a war of attrition that is approaching its 1,000-day milestone next month.

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Its slow but relentless drive deeper into Ukraine’s eastern Donetsk region is stretching Ukraine’s resources just as some of Kyiv’s key Western partners are being distracted by domestic concerns and Middle East wars.

Ukraine is building up its own arms industry, and authorities have identified drones as an important aspect of that.

“Among the key areas identified are drones for our army, and this should be a supply that not only constantly increases in volume, but also evolves and develops in line with the demands of war,” Ukraine President Volodymyr Zelenskyy said in a video address late Tuesday about weapons production.

The Russian military has also improved its drones’ capabilities and expanded their use.

Russian drones targeted Ukraine’s southern Odesa region for the third night in a row on Tuesday, injuring five people, regional Gov. Oleh Kiper said.

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However, Ukraine’s air defenses have proved resilient against drones. The Ukrainian air force said Wednesday it shot down 21 out of 22 drones that Russia launched over three Ukrainian regions.